ABOARD THE USS OSCAR AUSTIN IN THE BALTIC SEA — As a line medic for a Marine platoon in Iraq 10 years ago, Petty Officer 1st Class Randall McClain treated the wounds of war, from blunt trauma to lacerations and an amputation.

Now the senior medic aboard this guided-missile destroyer, the 39-year-old from Colorado deals with seasickness, illness and the occasional light injury from accidents. He is, by his own admission, a little bored.

“There are those who belong on the ship, those who belong on ‘greenside’ and those who belong in hospitals,” McClain said, using the term for a sailor embedded in a Marine unit.

As the U.S. prepares to withdraw its last combat troops from Afghanistan, the experience of Navy “greensiders” and others who have deployed on the ground over the past 13 years can be lost within a service whose wartime experience was mostly at sea. Now working in hospitals and chapels and aboard ships like this one, their experiences set them apart from their peers.

The Navy’s primary role in Iraq and Afghanistan was at sea, supporting flight operations, logistics and special operations. Its work was critical and intense: Between 2001 and 2011, the service was second only to the Army in the number of “troop-year” deployments.

The Navy assignments were generally less dangerous than those of soldiers, Marines and special operations forces. Those who did deploy were typically “individual augmentees” who rounded out commands by filling support roles such as military police, hospital corpsmen or even cooks. Some augmentees were part of the Navy’s Fleet Marine Force, a group of chaplains, hospital corpsmen and religious program specialists that regularly works with Marine units.

The Navy says it has deployed 78,000 sailors as individual augmentees since September 2001. Most assignments came during the height of the Iraq and Afghanistan wars, between 2006 and 2010, when the Navy assigned 54,000 individual augmentees, according to CNA Analysis, a firm specializing in Navy research.

Navy chaplain Lt. Autumn Butler-Saeger, 39, of South Carolina, deployed to Iraq in 2008 as the religious leader for a supply battalion of 1,100 Marines and civilians in Iraq’s Anbar province.

She recalls holding services in a plywood chapel, counseling distraught Marines and occasionally riding along with logistics convoys. Today, the chaplain is aboard the Oscar Austin, and she says her time in Iraq gives her perspective when conditions are difficult at sea.

“It was always funny to me to hear sailors complain about deployment when you had a hot meal three times a day, you had a semi-comfortable rack and you didn’t really worry about taking incoming fire,” she said.

Petty Officer 1st Class Douglas Edmonston was an armed guard for Navy chaplains serving Marines in Iraq. Over two six-month tours in the country, he often volunteered to fill out patrols or stand guard. Surrounded by Marines during his early years, he had trouble readjusting to some aspects of Navy life, including the level of respect between junior and midgrade enlisted. He immersed himself in Marine culture, which made readjustment to some aspects of Navy life difficult.

“A corporal tells a lance corporal to do something and the lance corporal jumps to it,” he said. A third-class petty officer tells a seaman to do something, you might have to tell him why.”

Now a career counselor aboard the Oscar Austin, Edmonston said Fleet Marine Force sailors have an easy rapport and mutual respect when working together on a deployment like this. He and corpsman McClain got along easily when they met.

The adjustment is often more difficult for corpsmen, who have played a more intense role in Iraq and Afghanistan, said Vice Adm. Bill Moran, the service’s chief of naval personnel.

“If you look at the corpsman rating, of the injuries, fatalities, casualties ... in the Navy outside of SEAL and EOD (explosive ordnance disposal), it’s the corpsman community that’s paid the highest price.”

McClain, from Grand Junction, Colo., knew he wanted to work with Marines when he joined the Navy. His chance came after assignment to a naval hospital in Portsmouth, Virginia, when he became an augmentee with the 1st Battalion, 8th Marines and went to Iraq in 2003 as a line medic.

McClain patrolled with his platoon in Haditha and Fallujah, enduring the stress of battle and experiencing injuries much different than those at the hospital. At first a “corpsman” to his Marines, he later became “Doc,” the term of endearment earned by line medics.

“I think it really shaped the way I act, the way I think,” he said.

Moran said sailors with downrange experiences will ultimately be a benefit to the Navy.

“We are far more joint and (far) better as a Navy for that experience,” he said.

McClain hopes his next assignment will be with a Marine unit. He likes the idea of getting back out to the field, although assignments are harder to come by as Afghanistan winds down and as he progresses in rank.